2015 Toyota RAV4 - Rear lift

The power lift gate on my 2015 Rav 4 has stopped working. It was working sporadically. I took it to the dealer and they said it only didn’t work twice and now it’s working. It has now stopped working completely. I can’t even open it manually. They couldn’t find anything wrong as far as codes etc. Not sure how to proceed. I have an extended warranty and it should be covered if they could determine the problem.

If the power back door won’t open with the switch or manually it is not operational, if you were able to demonstrate this to the service department then “they couldn’t find anything wrong” seems to be questionable. How can you accept the vehicle back if the back door is still inoperative?